Distributed storage systems use hardware such as a central processing unit (CPU), one or more disc controllers, and a plurality of data storage arrays providing bulk storage. Computer program code operating on the CPU and/or disc controllers controls the manner in which user data is stored and accessed on the bulk storage. User data can be stored in various fault tolerant schemes, such as in redundant array of independent drive (RAID) formats, for example. Multiple RAID formats can advantageously be employed concurrently within the data storage system. The rate at which the bulk storage can be dynamically allocated, as well as the amount of available storage capacity, both significantly contribute to the marketability of the storage system.
The first direct access storage device, IBM's RAMAC in 1957, had a 5 megabyte storage capacity existing on fifty 24 inch data storage discs. By the 1980s, the rate at which areal density capabilities progressed yielded a single 5.25 inch disc with the same 5 megabyte storage capacity. The industry has continued to evolve into ever-smaller form factors according to a standardized scaling methodology. Today, the 5.25 inch form factor is obsolete, having been replaced with the 3.5 inch and 2.5 inch form factors, and more recently with sub 1.8 inch form factors.
The evolution driving the scaling methodology has been skewed by the proliferation of consumer computer products employing the disc drives. That is, increased areal density has permitted decreased disc size, without penalty to storage capacity, and rotated at increased velocity with potentially reduced or constant power consumption. The increased rotational speed increases processing performance by reducing latency lags. The smaller size actuators offer improved seek time performance.
In continually pushing to make the discs smaller and spin them faster, power consumption has in fact become the baseline standardization design point, limiting the number of discs and the speed at which the discs can be rotated without exceeding a reliable operating temperature.
Accordingly, data storage arrays providing bulk storage have followed the same evolutionary path—that of seeking to continually reduce the size of the storage discs without loss of storage capacity in order to pack more drives within the array. In other words, the evolutionary goal has been to increase the spindle density within the array. However, as improvements in areal density have slowed, the demand for more capacity and faster processing capability by distributed storage systems remains a market factor. What is needed is a solution that optimizes both the processing speed and the storage capacity as primary design points, wherein power consumption and the associated heat dissipation becomes a tertiary consideration. It is to these improvement features that the embodiments of the present invention are directed.